Composite aluminum tower and the like



B. BAXTER Nov. 6, 1962 COMPOSITE ALUMINUM TOWER AND THE LIKE 5 Sheets-Sheet l Filed July 21, 1953 ATTORNEYS' Nov. 6, 1962 B. l.. BAXTER 3,062,335

COMPOSITE ALUMINUM TOWER AND THE LIKE Filed July 2l. 1958 5 Sheets-Sheet 2 INVENTOR.

BRUCE L. BAXTER www OW ATTORNEYS` Nov. 6, 1962 B. L. BAXTER COMPOSITE ALUMINUM TOWER AND TME LIKE 5 Sheets-Sheet :5

Filed July 21, 1958 M2 loeF'G 722 |52\ FIG Mo A FIG. IO

FIG. 9

93 INVENTOR. .92 BRUCE L. BAXTER FIGQG FIG. 8

ATTORNE YS B. L. BAXTER Nov. 6, 1962 COMPOSITE ALUMINUM TOWER AND THE LIKE Filed July 21. 195s 5 Sheets-Sheet 4 FIG. l2

FIG. I4

INVENTOR.

BRUCE L. BAXTER BY g( l ATTORNEYS Nov. 6, 1962 B. l.. BAXTER 3,052,335

COMPOSITE ALUMINUM TOWER AND THE LIKE Filed July 21. 1958 A l 5 Sheets-Sheet 5 '8 \MX VVVWV 3 |84 222 222 las f I U A D --vr n Q A U l J M /l A 50 52 56 IN VEN TOR. BRUCE L. BAXTER ATTORNEYS 3,062,335 CUMPOSITE ALUMINUM TOWER AND THE LIKE Bruce I.. Baxter, Louisville, Ky., assignor to Reynolds Metals Company, Richmond, Va., a corporation of Belaware Filed July 21, 1958, Ser. No. 749,693 Claims. (Cl. 189-12) The use of aluminum in structures, such as towers, bridges, buildings, etc., has been limited mainly because of two factors. One factor is the relatively higher cost of aluminum as compared to steel. 'Ihe other factor is that the modulus of elasticity of aluminum is only approximately one-third that of steel. The inherent advantages of aluminum, such as its light-weight, non-corrosiveness, elimination of the necessity for painting, negligible maintenance even in Seacoast areas, and many other advantages have been insufficient to offset the above factors of higher cost and lower modulus of elasticity.

A new and useful composite structure., according to this invention, utilizes aluminum in a new combination with other materials, such as steel with or without concrete, and/ or their equivalents so that, for the rst time, the inherent advantages of aluminum may be used economically in the aforementioned structures, while -retaining the strength and low cost of steel. The steel used is encased with the aluminum components, so corrosion is eliminated and strength is retained.

Hence, an object of this invention is to provide a unit for the erection of such structures in which a tubular body of aluminum mesh surrounds a plurality of linear members made largely of aluminum, which linear members are substantially parallel to the axis of said tubular body, and which linear members maintain said tubular body in highly tensioned condition to impart great strength to the unit.

Another object of this invention is to provide a unit according to the foregoing object in which one, or more, of said linear members contains a core of steel, or its equivalent.

Another object of this invention is to provide a unit according to the foregoing objects in which one, or more, of said linear members contains a body of concrete or its equivalent.

Another object of this invention is to provide a unit for the erection of such structures which is provided with a pair of spaced load bearing members lying in a rst plane and each including a centrol core made largely of steel, or its equivalent, which is surrounded by and spaced from a casing made of aluminum or its equivalent, these load bearing members being spaced by bar-like members made of aluminum which extend between the members, together with a pair of spaced parallel tensioning members lying in a second plane periendicular to the first plane, these tensioning members being laterally adjustable by longitudinally adjustable spacing bar-like members, together with an aluminum mesh surrounding the load bearing members and the tensioning members and being tensioned by lateral adjustment of the tensioning members.

Another object of this invention is to provide a unit according to the foregoing object in which a body of concrete is placed within the load bearing members and substantially surrounds the steel core.

Another object of this invention is to provide a structure made of a plurality of linearly aligned and joined units of the character set forth in the foregoing objects.

Another object of this invention is to provide a tower made of a plurality of substantially vertically aligned and joined units of the character above set forth.

Another object of this invention is to provide a tower made of a plurality of columns, each column being made States Patent ice of a plurality of substantially vertically aligned and joined units of the character above set forth.

Another object is to provide a tower according to the foregoing object in which the columns are joined by a transversely directed unit of the character above set forth.

Further objects will become apparent as the description proceeds with reference to the accompanying drawings in which:

FIGURE l is an isometric projection, somewhat diagrammatic, of a portion of one of the units, with the mesh broken away for clearness.

FIGURE 2 is a top View of one of the units.

FIGURE 3 is a vertical cross-section taken along the line 3 3 of FIGURE 2, showing a lower unit with a central portion broken away and with an end portion of an upper unit aligned and joined thereto, the mesh also being broken away.

FIGURE 4 is a vertical cross-Section of a unit taken along the line 4 4 of FIGURE 2, with a portion of the unit and mesh broken away.

FIGURE 5 is a side view of one of the intersections of' a suitable aluminum mesh, or expanded metal used with this invention.

FIGURE 6 is a diagrammatic elevation of a power transmission tower made according to this invention.

FIGURE 7 is a top View of the tower of FIGURE 6.

FIGURE 8 shows a portion of a tower similar to that illustrated in FIGURE 6, and having a slightly different joint construction.

FIGURE 9 is a side elevation of another embodiment of a tower made according to this invention.

FIGURE 10 is a side elevation of the tower shown in FIGURE 9.

FIGURE 11 is a top view of the tower shown in FIG- URE 9.

FIGURE l2 is a horizontal cross-section of one of the box-like members.

FIGURE 13 is a cross-section, in enlarged scale, taken along the line 13-13 of FIGURE l2.

FIGURE 14Vis a horizontal cross-section of the tensioning members, with parts broken away.

FIGURE l5 is a cross-section taken along the line 15-15 of FIGURE 14.

FIGURE 16 is a detail vertical cross-section of a construction for joining the steel cores of abutting units, the Alower unit being shown in dotted lines.

FIGURE 17 is a top plan view, on an enlarged scale, of a portion of FIGURE 11.

FIGURE 18 is a cross-section taken along the line i8-18 of FIGURE 17.

A unit 20 may be used by itself or with other units 2@ for the erection of structures such as towers, bridges, buildings, etc. By way of example, a plurality of such units 20 may be aligned and joined to form the transmission towers illustrated in FIGURES 6 through l1. These units may also be used to form other forms of towers such as stadium lighting towers, TV tower structures, street and highway lighting towers, railroad signal towers, electric railroad towers. The units may also be used to form any structure, such as roof trusses, building columns, etc. where maximum structural strength with minimum weight and corrosion is desired. The unit 20 may be twelve feet long, by way of example, when used to erect towers as shown in FIGURES 7-11. (All other dimensions herein given are also by way of example only, and are not intended to limit the scope of the invention.)

Reference is made to steel herein by way of example of relatively strong corrosive metals or alloys. Likewise, reference is made to aluminum herein by way of example 3 of substantially less strong and practically non-corrosive metals or alloys.

The units 20 preferably are made of a pair of spaced, parallel, linear, load bearing box-like members 22 and 24 which lie in a common plane, which may be a vertical plane. The members 22 and 24 are substantially identical, except for certain details which have been added to the members 22, and which may or may not be present in the members 24, as will become apparent. The members 22 and 24 include a central core 26, FIGURES 12 and 13 in particular, made largely of steel. The core 26 may take the form of a steel channel which may be twelve feet long. The core or channel 26 is surrounded by a box-like casing made of aluminum. This casing may include a larger U-channel 28 which may be four inches wide, six inches deep and twelve feet long, and this may be made of solid aluminum plate, ls inch thick. A second aluminum channel 30 is secured by bolts or self-tapping screws 32, or the like, to the channel 28, as indicated in FIGURE 12, so the aluminum box-like casing is substantially four inches by six inches in crosssection more or less, and twelve feet long, by way of example. Aluminum rods 34, one-half inch in diameter for example, pass through the flanges 36 of the channel 26 and through the sides of channel 28, where the rods 34 are threaded and receive aluminum nuts 38 for securing the rods 34 in place. Insulation, in the form of neoprene sleeves 40 and neoprene sheets 42, is placed between the surfaces of the rods 34 and the surfaces of the channel 26, to prevent galvanic action. The rods 34 may be placed, for example, two feet center to center. They may extend a distance of 41/2 inches or more from the casing 2S to provide a ladder along the tower. Another set of aluminum rods 34a are used in the box-like member 24, being substantially identical with the rods 34, except that they need not be as long, and may not extend outwardly as far as the rods 34, if no ladder is required on that side of the unit 20.

Under certain conditions, during the erection of the tower, the box-like members 22 and 24 may be filled with concrete 43, with a concrete gun, if desired, this preferably being done after complete assembly of the tower. Alternatively, the concrete may be inserted at intervals during the erection of the tower.

Spacing bar-like members 44, made of aluminum, extend between and may be secured to the load bearing members 22 and 24. These spacing bar-like members may maintain the box-like members 22 and 24 a distance of five feet. The spacing members 44 may be made of aluminum tubes 114. inches in diameter, and they may be placed at four foot intervals, more or less, along the longitudinal axis of the units. These spacing members 44 may pass through openings 46 in the channels 30, and they may have openings 48, FIGURE 13, through which the rods 34 pass. The rods 34 longitudinally fix the spacing members 44 within the box members 22 and 24. The rods 34a likewise pass through similar openings at the ends of the spacing members 44 within the box 24, as is apparent. The concrete heretofore mentioned is not inserted in the box-like members 22 and 24 until after the spacing members 44 have been placed and secured within the boxes 22 and 24. This concrete additionally axially fixes the spacing members 44 within the boxes.

A pair of aluminum spaced parallel linear tensioning members and 52 may be arc-shaped, as shown in FIG- URE 14, with strengthening flanges 54 along their edges. In the example given, they may be made of solid aluminum plate 1/s inch thick and may be live inches wide between flanges 54 and S4 and they also may extend a distance of twelve feet longitudinally for the production of a unit 2t) suitable for towers such as shown in FIG- URES 6 through ll. The box-like members 22 and 24 may lie in a rst longitudinal or vertical plane, and the tensioning members 5t) and 52 may lie in a second longitudinal or vertical plane, substantially perpendicular to the rst plane.

Longitudinally adjustable aluminum spacing bar-like members 56 extend between and laterally adjust the tensioning members 50 and 52. For example, the members S6 may be aluminum tubes 11/2 inches in diameter. An internally threaded thick or short tube or nut 58 is welded at one end of the tube 56 and receives the externally threaded bolt 60. This bolt 66 has a square-shaped extension 62 which passes out through an opening 64 made in the plate 66 and through a similar opening 68 made in the spacing member 52, and in the mesh to be described, if necessary. A washer 70, with a square opening snugly fitting over the extension 62 engages the side face of the plate 66. The effective length of the bar-like members 56 may be varied by turning the extension 62 with a wrench or the like, as is apparent. Another plate 66a receives the other end of the tube 56 in a circular recession 67. The plates 66 and 66a have their outer edges curled to match the inner faces of the members 5t? and 52, as is apparent.

The spacing members 44 and 56 preferably are spaced in pairs substantially four feet apart along the unit 20. The members 44 and 56 at the ends of the units 2G are a few inches away from such ends. When units 20 are aligned and joined, two pairs of these members 44 and 56 are close together, as shown near the top of FIG- URE 3.

An aluminum tension sheet, or mesh 72 surrounds the bearing members 22 and 24 and the tensioning members 50 and 52 and preferably is tensioned by lateral adjustment of the tensioning members S0 and 52. For example, this sheet or mesh 72 may be made of expanded aluminum sheet and may be wrapped horizontally around the members 22, 24, 50 and 52, with the ends of the mesh overlapping along the outer edge of member 22, FIGURE 12. These ends are clamped by aluminum bolts 74 with aluminum lock washers 76 therebetween. The mesh 72 around each unit 20 may be formed by three sheets four feet wide, wrapped transversely around the outside of the unit 20 with their side edges adjoining each other, as indicated by the dotted lines 77 in FIGURE 1. The four-foot wide mesh sheets are economical and convenient and are a present article of commerce.

The bolts 74 which hold the end edges of the mesh sheets may be spaced five inches center to center longitudinally along the outer edge of the member 22. However, if a cross member is to be attached thereto, as indicated in FIGURES `6 to 11, these bolts 74 may be spaced a slightly different distance properly to receive the main members of the cross structure without interfering with the attachment thereof, as will become apparent.

The expanded mesh 72 preferably has its members 78 diagonally with respect to each other at as indicated in FIGURE 5. The side edges of the mesh, which are indicated by the numeral 77 in FIGURE 1, may be attached to each other by any suitable securing members, if desired. Alternatively, if desired, a relatively narrow band of mesh, not shown, may be placed outside the edges 77 to form an overlapping and strengthening zone at this place. Alternatively, if desired, the mesh 72 may be a single sheet twelve feet in width and wrapped around the unit 20 to extend from one end to the other of the unit 20. The edges of the mesh 72 of adjacent units 2G may be likewise joined or reinforced.

The diagonal members 78 of the mesh 72, FIGURE 5, preferably are placed at a 45 angle with respect to the horizontal or transverse plane of the tower, when the tower is in substantially vertical position. The members 78 then are parallel to the lines of stress under these conditions and utilize the maximum strength-weight eiciency of the mesh.

If desired, U-bolts 80, FIGURES 2 and 3, may be placed at the intersections of adjacent bars 44 and 56 to straddle and lock both bars. A plate 82, with proper holes therein, may be placed over the ends of the U-bolt, ntllt the lock nuts 84 may be secured at the ends of the In manufacture, the units preferably are completely assembled at a factory. If transportation permits, the units 20 may be of the length of the iinal structure, in Whlch case no further units are aligned with each other to make the structure. However, if transportation does not permit this, then the units 20 may be shorter than the final structure or tower, and may be aligned with each other and secured to each other, for example, in a manner to be described to produce elongated structures such as the towers shown in FIGURES 6 through 1l.

Preferably the units 20 are assembled by securing their longitudinal members 22, 24, 5t) and 52 together and then tensioning the mesh around them to about 40% of its tensile strength. This tensioning is accomplished by laterally moving the tensioning members Sil and 52 away from each other by longitudinal adjustment of the spacing bar-like members 56 by turning the member 62 with a wrench or the like. This tensioning action on the mesh 72 greatly increases the strength of the mesh and of the entire unit 20 as a supporting structure.

The units 20 may be aligned with each other to produce longer structures such as the towers heretofore mentioned. By way of example, the units 20 may be secured to each other by the means shown in FIGURE 16. The steel channels 26 of adjacent units Ztl may be bolted to each other by means of a single plate 84, a single plate 86, or by the use of both plates 84 and 86, as desired. The positioning of the bars 44 is selected so that the joining structure of FIGURE 16 may be used without interference from such bars 44. if plate 84 only is to be used, this plate is bolted to the channel 26 ofthe upper unit 20 before assembly with the lower unit as indicated in full lines in FIGURE 16. Preferably a pair of bolts or screws SS and a pair of bolts or screws 959 are tapped into the channel 26 and locked in place by lock washers, or by the locking action of the selfdocking tap screw or bolt. The bolts or screws 88 and 96 preferably freely pass through holes in the plate 84 and threadedly engage holes in channel 26 to permit complete tightening of the bolts. Openings 92 are provided in the outer channel 2S and the mesh 72, so a tool may be used to hold, insert and turn the bolts S8 and 9@ and to secure them in place. When the plate 84 has been so secured, the upper unit 211 is mounted on a lower unit 20 with the plate 84 adjacent the channel 26 of the lower unit 20, FIGURE 16. This lower channel 26 is provided With threaded holes which align with the slightly larger unthreaded holes in the plate 84, and bolts or screws 93, in pairs, are inserted through openings 92 in the lower casing 28 and mesh 72 of the lower section 20 and are screwed in and tightened similarly to bolts 8S and 91B.

The same procedure is followed if the plate 86 is used by itself, except that the holes in plate 86 are threaded and the holes in the channels 26 are slightly larger and unthreaded. If both the plates S4 and 36 are used, then the holes in plate 86 are threaded and the holes in channels 26 and plate 84 are slightly larger, and Unthreaded. This permits a tight clamping action by the bolts to secure the channels 26 and the plate or plates S4 and/ or 86 together.

The ends of the tensioning members 50 and 52, of adjacent sections 20 also may be secured to each other by an inner plate construction substantially similar to plate 36 and bolts 84, etc., illustrated in FIGURE 16, except that corresponding plate for members 50 and 52 is curved to match the curvature of the members Sil and 52, as is apparent.

The units 2t) may be aligned and joined to form the towers shown in FIGURES 6 through l1. In FIGURES 6 and 7 the lower tive units 20 are shown slightly converging toward each other. Any number of additional sections 20 above this converging section may be placed vertically parallel to each other and may extend upwardly any desired distance. Additional fractional units may be used at the top. The adjoining edges 160 of the lower units 20 in FIGURE 6 are shown parallel to the ground line 102. This produces a substantially negligible divergence from a right-angled relationship between the edges of the units and their longitudinal axis. They may be built into the units, if the angle requires it. Ordinarily, the divergence from a right angle is substantially negligible. Likewise, the adjoining line between the iifth upper unit 20 and the sixth unit has a slight divergence which can be built into the unit 5, if necessary.

The transverse members 11M and 165 may be of any well known and standard construction and may be attached to the box-like member 22, or the box-like member 24, or both. For example, spanning aluminum bars 106 and 107 may be secured to either of the box-like members 22 or 24, or both, as indicated in the top view in FIGURE 7. The extension 108 may be made up of two converging bars 1118 secured to the box-like members 22 and 24 at their inner ends and secured to each other at 110 at their outer ends, as indicated in FIGURE 7. Similarly, the bars 112 may be two bars converging downwardly toward each other to the point 110 where they are secured to each other, and to the members 1&8. The inner, upper ends of members 112 are secured and extend to the members 22 and 24 adjacent the ends of members 106, as is apparent. The top transverse member 105 is substantially the same, except that the longer extensions are at the top instead of at the bottom, and are somewhat shorter than those of sections 104, as is apparent. Preferably, all of the members of the transverse members 104 and 105 are made of aluminum bars or channels, as is desired. If desired, vertical and horizontal cross-bracing, not shown, may be included in these constructions. Alternatively, the transverse members 161i and 105 may be placed on only one side of the tower, in which case member 108 may be rigid and integral with member 107 and member 112 may be rigid and integral with member 106.

FIGURE 8 illustrates a construction similar to that shown in FIGURES 6 and 7 except that the joining edges of the units 20 are shown at right angles to the axes of lower and upper sections 2th. The support at the ground, not shown, may be made to accommodate the slight inclination of edges 12). A special joining section 122 may be provided with a slight angle at 124, so that its lower edge 126 may be joined at right angles with the lower sections Ztl and its upper edge 128 may be joined at right angles with the end edges of the upper units 20, as is apparent. These two special sections or units 122 may be made at the factory, if desired.

FiGURES 9, l0 and 1l show a transmission tower in which the vertical columns are made parallel to each other throughout their length and are perpendicular to the ground line so the edges 13h of the units 211 are at right angles to the longitudinal axes of the units 2?. One, or more, transverse line supporting members 132 may be secured to the tower to support the electric lines. These members 132 may be of the usual construction, as previously described in connection with FIGURES 6 and 7, or may use one or more of units substantially similar to units 20. The joining constructions between the vertical and transverse members of the tower may be as shown in FIGURES 17 and 18. The cross-member 132 may be a single, extra long, unit similar to unit Ztl. Alternatively, it may be a plurality of units similar to units Ztl aligned and joined With each `other substantially as previously described, and illustrated in FIGURE 16. In FIGURES 9 through 11, and 17 and 18, the unit 132 is shown substantially with the same cross-section as the units 2d. However, such unit 132 may be of less cross-sectional dimension. The corresponding members in unit 132 are indicated by reference numerals substantially the same as in the units 20, except that the corresponding members have a prefix 2 of 200 added thereto. For example, the box-like member 222 of unit 132 corresponds in construction substantially to that of box-like member 22 previously described. The box-like member 224 of unit 132 corresponds to the unit 24 previously described. The tensioning members 250 and 252 of unit 132 correspond to units Sb and 52 previously described and likewise the bar-like members 244 and 256 correspond to the members 44 and 56 previously described. All other identified or unidentified members may be substantially the same. The length of the members 244 and 255 may be different from that of members 44 and S6 as is obvious, and as required by the strength needed in the transverse member 132.

In order to permit the transverse unit 132 to be partially overlapped with the adjacent unit 29, the mesh 272 of unit 132 is cut away along the lines 15G and 152, FIG- URE 17, in order to permit the mesh 72 and the bex-like member 22 of unit 26 to be overlapped into member y132, so the member 22 may abut the sides of box-like members 222 and 224. The edges 154 and 156 of the mesh 272 on the far side of member 132 may be closely adjacent, and may be actually secured to each other in a manner as previously described. The member 252 is cut away at 16"@ and 162 to permit the mesh 72 to overlap into member 132.

If desired, the adjacent mesh constructions 272 of FIG- URES 17 and 18 need not extend diagonally as indicated at 150 and 152 but may extend perpendicularly from the cut ends 16@ and 162 of member 252 and may extend perpendicularly directly across to the other tension member 251i. The box-like members 222, 224 and the tension member 250 are made particularly strong in the neighborhood of the intersecting points of the vertical and transverse members which are illustrated in FIGURES 17 and 1S.

In FIGURES 17 and 18, the box-like members 222 and 224 of the transverse member 132 are secured to the vertical box-like member 22 of the vertical section 21B by means of U-bolts 18e which pass around the box-like member 22 at 132 and which pass through rectangular plates d which are placed adjacent the side of the boxlike members 222 and 224, Suitable lock-nut constructions 186 tighten and lock these securing means in place. One or more U-bolts 130 may rest directly on a rod 34 or 343:1 to prevent any vertical displacement of the transverse member 132.

Alternatively, the cross-member 132 of FIGURES 9 through ll and 17 and 18, may extend only between the vertical columns of units 2t), and the extensions 170 and 172 may `be omitted, and all of the transmission lines may be hung between the vertical column. Under such conditions, the vertical columns of unit may be spaced sufficiently far apart to prevent arcing from the electric cables, as is obvious.

Transverse members similar to 132 may be used in lieu of the transverse members 104 and 105 of the towers shown in FIGURES 6, 7 and 8 and, conversely, the transverse members ati-t and 105 of FIGURES 6, 7 and 8 may be use-d in the tower structure of FIGURES 9, l0 and ll in lieu of the cross-member 132, as is obvious.

In the towers illustrated, the strength, weight, and thickness of the components of the units 20 may be reduced in each higher unit. On the other hand, the cross-sectional dimensions of the unit 2t? preferably is maintained uniform throughout the height of the tower. For example, the lowest unit 20 in the towers may have a steel channel 26 weighing 7.25 lbs. per linear foot. The next higher unit 2t? may have a steel channel of 6.25 lbs. weight per foot. The third unit 20 may have a steel channel of 5.4 lbs. weight per foot and the reduction of the weight of this channel 26 may continue to some extent as the height increases in the tower. Similarly, the expanded metal mesh of the lowest unit 26 may ybe .183 inch thick, the next higher unit may have mesh .140 inch thick, section 3 may have mesh of .090 inch thickness, and so on.

3 The other components of the units may be reduced in strength or may be retained of the same strength as desired.

The usual high tension transmission electric lines or cables may be hung with insulators from the ends of the transverse members 184 and 105 and 132 and from the center part of such transverse members. Generally, the inner transmission line may be grounded in the usual manner.

Single columns, double columns, and etc. may be used to produce other types of towers of the character previously set forth.

Units and structures are thus provided by this invention which have all of the advantages of strength and loal cost of steel, and all of the advantages of non-corrosiveness, low cost maintenance, freedom from painting, etc., which are inherent in aluminum.

While the embodiment of this invention now preferred has been disclosed, as required by statute, other forms may be used, all coming within the scope of the claims which follow.

What I claim is:

l. A unit for the erection of structures comprising: a pair of spaced, parallel, linear, load bearing members lying in a first plane and each including a central core made largely of steel, surrounded by a casing made of aluminum, with a body of concrete within said casing; aluminum spacing bar-like members extending between said load bearing members and maintaining said load bearing members in spaced relationship; a pair of spaced parallel linear aluminum tensioning members lying in a second plane substantially perpendicular to said first plane; longitudinally adjustable aluminum spacing bar-like members extending and laterally adjusting said tensioning members; and aluminum mesh surrounding said load bearing members and said tensioning members, said adjustable members being adapted to selectively vary the distance between said tensioning members to vary the tension of said mesh.

2. A unit for the erection of structures comprising: a pair of spaced, parallel, linear, load bearing members lying in a first plane and each including a central core mad-e largely of relatively corrosive and strong metal, surrounded by a casing made of relatively non-corrosive and less strong metal, with a body of concrete within said casing; relatively non-corrosive and less strong metal spacing bar-like members extending between said load bearing members and maintaining said load bearing members in spaced relationship; a pair of spaced parallel linear relatively non-corrosive and less strong metal tensioning members lying in a second plane substantially perpendicular to said first plane; longitudinally adjustable relatively non-corrosive and less strong metal spacing bar-like members extending and laterally adjusting said tensioning members; and relatively non-corrosive and less strong metal mesh surrounding said load bearing members and said tensioning members, said adjustable members being adapted to selectively vary the distance between said tensioning members to vary the tension of said mesh.

3. A unit for the erection of structures comprising: a pair of spaced, parallel, linear7 load beainrg members lying in a first plane and each including a central core made largely of steel, surrounded by a casing made of aluminum spaced from said core; aluminum spacing bar-like members extending between said load bearinfT members and maintaining said load bearing members in spaced relationship; a pair of spaced parallel linear aluminum tensioning members lying in a second plane substantially perpendicular to said first plane; aluminum spacing bar-like members extending between and spacing said tensioning members; and aluminum mesh surrounding said load bearing members and said tensioning members, said members extending between said tensioning members being adapted to selectively vary the distance between said tensioning members to vary the tension of said mesh.

4. A unit for the erection of structures comprising: a pair of spaced, parallel, linear, load bearing members lying in a rst plane and each including a central core made largely of steel, surrounded by a casing made of aluminum spaced from said core; aluminum spacing barlike members extending between said load bearing members and maintaining said load bearing members in spaced relationship; a pair of spaced parallel linear aluminum tensioning members lying in a second plane substantially perpendicular to said rst plane; aluminum spacing barlike members extending between and spacing said tensioning members; and a relatively thin aluminum sheet surrounding said load bearing members and said tensioning members, said members extending between said tensioning members being adapted to selectively vary the distance between said tensioning members to vary the tension of said sheet.

5. A unit for the erection of structures comprising: a pair of spaced, parallel, linear, load bearing members lying in a rst plane and each including a central core made largely of steel, surrounded by a casing made of aluminum spaced from said core With a body of concrete within said casing; aluminum spacing bar-like members extending between and spacing said load bearing members; a pair of spaced parallel linear aluminum tensioning members lying in a second plane substantially perpendicular to said first plane; longitudinally adjustable aluminum spacing bar-like members extending and laterally adjusting said tensioning members; and a relatively thin aluminum sheet surrounding said load bearing members and said tensioning members, said members extending between said tensioning members being adapted to selectively vary the distance between said tensioning members to vary the tension of said sheet.

References Cited in the le of this patent UNITED STATES PATENTS 755,724 Tomlinson Mar. 29, 1904 791,975 Allen June 6, 1905 1,498,898 Young June 24, 1924 1,617,762 Kiefer Feb. 15, 1927 1,653,055 Macomber Dec. 20, 1927 1,936,272 Schulz Nov. 21, 1933 2,805,739 Dennison Sept. 10, 1957 FOREIGN PATENTS 611,907 Great Britain Nov. 5, 1948 163,278 Austria June 10, 1949 

